Semiconductor devices typically include openings that have been filled with polysilicon, which may form constituent parts of various electronic devices. The fill may include depositing a layer of silicon on side and bottom surfaces of the opening, with the layer filling in the opening from the sides and bottom as it grows. The growth of the layer may not be completely uniform, however, causing voids, such as seams, to form in the interior of the opening. In some cases, these voids may be caused by the deposition process, in which silicon may deposit at a higher rate at the top of the opening than at the bottom, thereby causing the top of the opening to close up first, leaving the voids in the interior of the opening.
FIG. 1 shows a transmission electron micrograph (TEM) cross-section of an opening filled with an as-deposited, amorphous silicon film. As seen in the circled region at the center of the cross-section, a void, a vertically-elongated seam in this case, is present. Such voids can adversely impact the electronic devices formed by the filled opening. Accordingly, there is a need for processes for forming silicon-filled openings, while leaving no or nearly no voids in the openings.